Laser clad knife guard

ABSTRACT

A cladded knife guard is provided. In one aspect, the invention provides for a knife guard that comprises a guard body that further comprises a base material. The base material includes a mounting bar that defines at least one bolt hole and at least one tine projecting forward from the mounting bar. The base material has a first hardness. A cladded material is formed on the base material. The clad material comprises a second hardness greater than the first hardness.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This patent application is a continuation of co-pending PCT Application No. PCT/US2015/018059, filed Feb. 27, 2015, which claims the benefit of U.S. Provisional Patent Application No. 62/050,687, filed Sep. 15, 2014, and U.S. Provisional Patent Application No. 62/050,880, filed Sep. 16, 2014, the entire teachings and disclosure of which are incorporated herein by reference thereto.

FIELD OF THE INVENTION

This invention generally relates to a laser clad knife guard for a sickle bar assembly.

BACKGROUND OF THE INVENTION

Knife guards are used in sickle style cutting systems. They act as the stationary surface for moving sickle blades to cut against or at least to protect or cover the sickle blades. Examples are shown in U.S. Pat. Nos. 6,962,040, 4,660,361, 7,478,522, and 8,464,506 the disclosures of which are incorporated by reference as the present invention may be applied and/or incorporated into these examples in various embodiments.

Knife guards are primarily constructed of steel and manufactured in a variety of ways including forging, casting, welded fabrication of stamped components, and machining. In some instances, a hardened plate is assembled into the guard to create a surface known as a ledger plate that the sickle runs on and the edge. Past efforts to improve the hardness of the shearing surfaces of the ledger plate have not met with the desired cutting efficiency or wear characteristics which in turn have resulted in increased costs in both harvesting and equipment repair and or replacement. Past efforts to improve the hardness of the ledger plate and in turn the ledger bars and shearing edges have included hardening via quench and temper or austemper, carbonizing or carbonitriding, induction hardening, flame hardening, or boronizing. In some cases, more than one of these treatments is performed on the part in order to impart varying properties within the knife guard.

With the exception of induction hardening, the remaining treatments are high heat processes of over 1500° F. and require the entire part to be raised into these temperature ranges. The knife guard in its original state contains internal stresses. Accordingly, distortion of the part is a factor with these processes. Distortion is not desirable where the knife guard provides a bearing surface supporting sliding movement and reciprocation of a sickle bar. The result is often additional machining or straightening processes to bring the part back within specification. These additional steps increase cost.

In the case of induction hardening, typically very elaborate induction coils and quenching processes are required to perform the process in a repeatable and predictable manner. Induction heat is a resistance type of heating. The result of this process along with flame hardening a heat affected zone which is driven deep into the part. In order to achieve the desired microstructure in knife guard material, a quench process must be used to reduce the internal temperature of the knife guard quickly enough to create the proper metallurgical transformation. In addition, the induction process focuses the energy in the thinner section of the knife guard edge resulting in the risk of melting the material at the edge. The depth of the heat affected zone also creates a similar situation to the previously mentioned treatments in that it causes stresses in the part to be relieved often resulting in distortion of the part.

BRIEF SUMMARY OF THE INVENTION

The present invention is generally directed towards cladding the knife guard in one or more select regions. Cladding may be deposited on an entire top surface of a ledger bar to improve the wear characteristics of the ledger bar. Additionally or alternatively, the cladding may be deposited along flank surfaces of each tine so as to laterally extend the flank surfaces, provide a top flank surface that extends the ledger surface and provides a hardened shearing edge so as to maintain the sharpness of the shearing edges of the knife guard.

In one aspect, the invention provides for a knife guard that comprises a guard body that further comprises a base material. The base material includes a mounting bar that defines at least one bolt hole and at least one tine projecting forward from the mounting bar. The base material has a first hardness. A clad material is deposited on the base material. The clad material is of a second hardness greater than the first hardness.

In an embodiment the knife guard may include a ledger surface that is adapted to bear against or at least face a sickle bar assembly. The ledger surface may include a region of the clad material formed integrally with an outer surface of the base material.

In another embodiment, the base material base material may be steel. The clad material may be at least 0.1 millimeter in maximum depth thickness along the base material and less than 3 millimeters. The depth measured in the direction of deposition.

Each of the tines may include a central protrusion and a pair of flank surfaces on either side of the central protrusion that extend toward a bearing surface. The flank surfaces may intersect the bearing surface at a shearing edge. The region of clad material may include at least one portion formed along and extending the flanks laterally so as to extend the ledger surface and form part of the shearing edge. The clad material may project horizontally outward from the base material to extend the flanks horizontally outward relative to the central protrusion.

The knife guard may further include a free region of base material that is not of the clad material. The free region being disposed above the central protrusion along the ledger surface and between first and second portions of clad material, the first and second portions being formed along the flanks so as along ledger surface and forming part of the shearing edge.

The knife guard may further include a trash bar that extends perpendicularly to an extension direction of the at least one tine and connects adjacent tines of the at least one tine. The free region may extend along the ledger surface and extending along a trash bar portion of the ledger surface defined by the trash bar. The trash bar is free of the clad material.

The knife guard may include a ledger bar that extends perpendicularly to an extension direction of the at least one tine, the ledger bar may define a ledger bar portion of the ledger surface. The ledger bar portion may form part of the region of clad material along a length and an entire top surface thereof.

Preferably, more than 30% of the ledger surface is free of the region of clad material.

The clad material on the flank surfaces of the knife guard may extend from the ledger surface at the shearing edge toward the central protrusion a width between 0.5 millimeter and 10 millimeter and may be between at least 0.1 millimeter and 3 millimeter in depth thickness on the flank surface. The depth may be perpendicular to the width.

The knife guard may further include a dilution zone wherein the clad material forms the dilution zone with the base material at a junction therebetween.

In an embodiment, over 85% of an outer surface of the knife guard may form an untreated region of base material. The clad material may be limited to less than 15% of the outer surface.

In another embodiment, the base material may have a hardness of less than 50 HRC and the clad material may have a hardness greater than 50 HRC.

In another embodiment, the at least one tine may comprise a plurality of tines with valleys between the tines. The at least one bolt hole may include a plurality of bolt holes that have respective bolt mounting centers aligned along a mounting axis that extends perpendicularly relative to a forward extending axis direction of the tines. The bolt holes may be formed in mounting bosses formed along the mounting bar. A connecting trashbar may extend perpendicularly relative to the forward extending axis direction and connect adjacent tines. The mounting bar may include a ledger bar. The ledger bar and the tines may define a ledger surface that extends in a plane. A sickle clearance channel may be formed between the ledger bar and the trash bar. Ribs at a bottom of the sickle clearance channel may connect the ledger bar and the trash bar.

The ledger bar may project from a mounting plate portion of the mounting bar and the mounting bosses may be formed into the mounting plate.

In an embodiment, each one of the pair of flank surfaces comprise a base flank surface and an extended flank surface. The extended flank surface extends laterally outward from the base flank surface relative to the central protrusion. The extended flank surface is comprised of the clad material.

Each extended flank surface includes a top extended flank surface that is coplanar with and forms part of the ledger surface.

Each of the top extended flank surfaces intersects with the extended flank surfaces at the ledger surface to form part of the shearing edge.

In an embodiment, the extended flank surface may extend from the ledger surface of each tine toward the central protrusion a depth between 0.5 and 10 millimeters. The extended flank surfaces may extend outwardly away from the base flank material and laterally away from the central protrusion to provide and extended flank surface depth between 0.1 and 3 millimeters but typically less than a millimeter.

In an embodiment, greater than 50% of each of the flank surface may be free of clad material.

In an embodiment, greater than 50% of each ledger surface may be free of clad material.

In another aspect, the invention provides a cutter bar assembly that includes a linear array of a plurality of the knife guards. The cutter bar assembly may include a cutter bar support that may have a mounting flange that extends in parallel relation to the linear array. The sickle bar assembly may extend in a longitudinal direction in parallel relation with the cutter bar support in order to reciprocate back and forth in the longitudinal direction for cutting. T sickle bar assembly may include a sickle bar and a plurality of sickle knives mounted to the sickle bar. The knife guards may be arranged in side by side relation and the sickle knives may be arranged in side by side relation. The knife guards and the sickle knives may be in vertically overlapping relation.

The sickle bar may slide along the knife guards along a region of clad material formed on an outer surface of the base material.

In yet another aspect, the invention provides a method of forming a knife guard. The knife guard comprises a guard body. The guard body may be comprised of a base material and may include a mounting bar that defines at least one bolt hole and at least one tine projecting forward from the mounting bar.

The method may include cladding with a laser a region of a second material on to the base material to provide a second hardness greater than the first hardness.

The cladding with the laser may include using at least one of the following lasers CO₂, YAG, Diode and Fiber.

The cladding may include targeting and confining the application of the laser to the region being of an outer surface of the guard body. The region may be less than 15% of an area of the outer surface.

The region is deposited along a perimeter of the ledger surface at the shearing edges to form a sliding interface with a sickle bar assembly that reciprocates relative the knife guard in use.

At least 30% of the ledger surface may include an untreated region free of cladding and wherein distortion may be eliminated or reduced such that subsequent machining or straightening operations are not conducted on the ledger surface after the cladding.

In an embodiment the region is deposited horizontally along opposing sides of the base material of the at least one tine, thereby forming a shearing edge with the second material.

Other aspects, objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings:

FIG. 1 is a schematic top view of a first portion of a knife guard according to an embodiment of the present invention with the laser hardened regions emphasized and illustrating the laser hardening tool angularly positioned to laser treat the ledger and or bearing surfaces of the tines.

FIG. 2 is a partial cross section of a front view of the knife guard of FIG. 1 emphasizing the cladding deposited on the flanks of the knife guard, with the ledger and bearing surface forming the top surface.

FIG. 3 is an enlarged view of the cross section of FIG. 2 further emphasizing the width and depth of the cladding on the flank surfaces of the knife guard, and exaggerated schematic “dilution zone” shown for metallurgical bonding.

FIG. 4 is a side elevation view of the knife guard of FIG. 1.

FIG. 5 is a schematic illustration of at least two portions of knife guards and sickle blades of an embodiment of the present invention, the distance between knife guards being potentially exaggerated (e.g. trash bars of adjacent knife guards my abut or almost abut each other at less than 1 cm in spacing.)

While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIG. 1, a laser clad knife guard 10 according to an embodiment of the present invention is illustrated. A knife guard 10 comprises a guard body 12 and is comprised of a base material 14 such as steel material, that includes a mounting bar 16, which defines at least one bolt hole 18 and at least one tine 20 projecting forward 56 from the mounting bar 16. The base material 14 has a first hardness 22 and a clad material 24 is deposited on the base material. The clad material 24 comprises a second hardness 26, greater than the first hardness 22 and can be deposited in horizontal strips running lengthwise from a rear portion toward the tip or front portion of the tine.

The knife guard 10 includes a ledger surface 28 that is adapted to bear against or at least face a sickle bar assembly 30. Typically the ledger surface 28 will come into contact with the sickle bar assembly 30 to guide or maintain linear reciprocating movement of the sickle bar assembly 30. FIG. 5 illustrates an embodiment of the present invention wherein the sickle bar assembly 30 moves over the ledger surface 28 of a knife guard 10. The ledger surface 28 includes a region of cladding 24 formed on the outer surface of the base material 14 to provide for the material of the second hardness 26. As shown in FIG. 3 the ledger surface 28 may be provided by respective coplanar regions of ledger bar portion 80 a and bearing surface portion 36 of the of tines 20.

Turning to FIGS. 2 and 3 the cladding 24 is shown in greater detail. A tine 20 comprising a bottom surface 33 (FIG. 4) that includes a central protrusion 32 and a pair of flank surfaces 34 on either side of the central protrusion 32 that extend toward a ledger surface 28. The flank surfaces 34 are comprised of a base flank surface 29 and an extended flank surface 31. The cladding 24 that makes up the material of the second hardness is deposited along each base flank surface 29 of the tine 20 to provide the extended flank surface 31. As best seen in FIG. 2, the extended flank surface 31 does not extend along the entire base flank surface 29 to the central protrusion 32. Instead, the extended flank surface 31 provides a width of cladding 24 that extends from the ledger surface 28 along the base flank surface 29 towards the central protrusion 32.

In an embodiment, the extend flank surface 31 may be of a width between 0.5 and 10 millimeters. In a preferred embodiment the depth may be between 2.5 and 6 millimeters, and in a more preferred embodiment between 4 and 5 millimeters.

Further, the cladding 24 deposited along the base flank surfaces 29 provides a top extended flank surface 35 on each side of the tine 20. The top extended flank surfaces 35 are coplanar with the ledger surface 28 and thus extend not only the flanks 34 but also the bearing surface 28 of the tines 20. In an embodiment a thickness 46 of cladding 24 provides for a maximum cladding depth 46 that extends outwardly from the base flank 29 to the extended flank surface 31 between 0.1 millimeters to 3 millimeters. In a more preferred embodiment the cladding width along the extended top surface may be between 0.1 and 1 millimeters.

Further, where the top extended flank surface 35 meets the extended flank surface 31 a shearing edge 38 is formed. Thus, the shearing edge 38 is comprised of the cladding 24. Accordingly, the cladding 24 provides the material of the second hardness that comprises the shearing edge 38. The hard shearing edge 38 provides the advantage of decreased wear when cutting crop and thus increased efficiency and lower overall costs with improved life of the tine 20. Further, because the cladding 24 also extends the ledger surface 28 of the tine 20 the shearing edges 38 of the ledger surface 28 wear more slowly when the sickle knives 78 (FIG. 5) slide over the top of the ledger surface 28. As discussed this provides the advantage of decreased wear of the ledger surface 28, increased cutting efficiency, and lower and less frequent repair costs due to the increased longevity of the tines 20 and their shearing edges 38 and ledger surfaces 28. It is readily apparent that the ledger surfaces 28 act as bearing surfaces for the sickle knives 75.

Turning briefly to FIG. 4, there the ledger bar 80 that makes up part of the overall ledger surface 28 is shown in side view to illustrate with particular emphasis the cladding 24 that is deposited on a top surface of the ledger bar 80. The cladding 24 is deposited along the entire top surface of the ledger bar 80 but it is not the intention of the present invention to limit the deposit of cladding to the entire top surface of the ledger bar 80. Depositing the cladding along the top surface of the ledger bar 80 provides the top surface with advantage of wearing more slowly when in contact with an opposed bearing surface of the sickle knives 75. As with the flanks 34, and shearing edges 38, the hard top surface of the ledger bar 28 decreases its wear relative to a ledger bar without cladding and thereby decreases repair and maintenance costs and overall harvesting efficiency.

Laser cladding technology is utilized to deposit the cladding along the flanks 34 and the ledger bar 80 as schematically illustrated in FIG. 1 with the laser tool 94. Laser cladding is the process of cladding material with the desired properties and fusing it onto the substrate by means of a laser beam. Laser cladding can yield surface layers that when compared to other hard facing techniques or standard blade material can have superior properties in terms of hardness, bonding, corrosion resistance and microstructure. Thus as schematically seen in FIG. 3, dilution zones 57 are formed with the base material 14 along the base flank surface 29 when the cladding 24 is deposited thereon. The dilution zones are areas where metallurgical bonding has occurred as a result of the deposited laser clad material 24. These areas provide the advantage of strong bonding and minimized distortion of the base material that as previously discussed result in the advantage of less or no post cladding machining and processing to correct distortion than other known process.

Thus, dilution zones 57 are present at the base flank surface 29 as shown in FIG. 3 where the laser clad 24 is deposited and along the top surface of the ledger bar where the cladding is deposited.

The hard/wear resistant laser clad material 24 referred to in various embodiments of the invention is material composed of a medium to high percentage of hard particles. These hard particles can be: Tungsten Carbide, Titanium Carbide, Chrome Carbide, Iron Carbide, Diamond, Ceramics, or any other high hardness particles in the range of HV 1200-2500 (Vickers scale hardness). The high hardness particles are then bonded and held in place to the base material through the metallurgical bond. In the alternative to carbides, powders of various metal alloys or other amorphous materials may be laser clad according to the present invention. Carbide alternatives as envisioned or discloses in U.S. Pat. No. 6,887,586 or U.S. RE 29,989 (see also U.S. Pat. No. 3,871,836), the entire teachings and disclosures of which are incorporated herein by reference.

The knife guard 10 may further comprise a free region 42 of base material 14 that is not a cladding. As illustrated in FIG. 1, the free region 42 may be disposed on and under, that is from the ledger surface 28 extending to the central protrusion 32 of the tine 20 and between the top extended flank surfaces 35. The free region 42 can limit distortion and cost associated with laser hardening operations.

FIG. 1 illustrates that the knife guard 10 may further comprise a trash bar 44 that extends perpendicularly to an extension direction 56 of the at least one tine 20 and connecting adjacent tines of the at least one tine 20. The free region 42 may extend along the bearing surface portion of ledger surface 28 that extends along trash bar 44. The trash bar 44 may be free of the cladding 24. As can be readily appreciated not every embodiment of tine 10 has a trash bar 44 with an associated ledger portion.

The mounting bar 16 includes a ledger bar 80 that extends perpendicularly to an extension direction 56 of the at least one tine 20. The ledger bar 80 defines a ledger bar portion 80 a of the ledger surface 28 wherein the ledger bar portion 80 a forms part of the region of cladding 24 along the length thereof. More than 30% of the overall ledger surface 28 may be free of the region of cladding 24. Not every embodiment of a cladded guard 10 has a ledger bar 80 and thus would not have a ledger bar portion 80 a that would be part of the cladding 24 or form part of ledger surface 28.

Over 85% of the outer surface of the knife guard 10 may form an uncladded region of base material 14. The clad material 24 may be limited to less than 15% of the outer surface of the knife guard 10, and often substantially less.

In an embodiment, the base material 14 may have a hardness of less than 50 HRC and the clad material 24 may have a hardness greater than 50 HRC. In a more preferred embodiment the clad material 24 may have a hardeness greater than 60 HRC. Some embodiments may be even greater than 70 HRC. The clad material has a hardness at least 5 HRC points higher than the base material and typically 10 HRC points or more, higher than the same base material.

The at least one tine 20 may comprise plurality of tines 20 with, as shown for example in FIG. 5, valleys 52 between the tines. The at least one bolt hole 18 may comprise a plurality of bolt holes 18 having respective bolt hole mounting centers aligned along a mounting axis 54, as shown if FIG. 1, that extends perpendicularly relative to a forward extending axis direction 56 of the tines 20. The bolt holes 18 may be formed in mounting bosses 60 formed along the mounting bar 16. A connection trash bar 44 extends perpendicularly relative to the forward extending axis direction 56 and connecting adjacent tines 20. The mounting bar 16 includes a ledger bar 80. The ledger bar 80 and the tines 20 define a ledger surface 28 that extends in a plane wherein a sickle clearance channel 62 is formed between the ledger bar 80 and the trash bar 44. Ribs 64 at a bottom of the sickle clearance channel 62 connect the ledger bar 80 and the trash bar 44. The ledger bar 80 projects from a mounting plate portion 66 of the mounting bar 16. The mounting bosses 60 are formed into the mounting plate 66.

FIG. 5 illustrates a cutter bar assembly 68 that includes a linear array of a plurality of knife guards 10 of an embodiment of the present invention. A cutter bar support 72 has a mounting flange 74 that extends in parallel relation to the linear array of knife guards. A sickle bar assembly 30 extends in a longitudinal direction 70 and parallel relation with a cutter bar support 72 in order to reciprocate back and forth in a longitudinal direction 70 for cutting. The sickle bar assembly 30 includes a sickle bar also commonly referred to in the art as a knife back 82 and a plurality of sickle knives 78 mounted to the sickle bar 82. The sickle knives 78 are arranged in side by side relation. The knife guards 10 are arranged in side-by-side relation. The sickle knives 78 are in a vertically overlapping relation to the knife guards 10. A portion of the sickle bar 82 rides inside the sickle clearance channel 62 while a surface of each of the sickle knives 78 rides over the ledger surface 28 of the knife guards 10.

An embodiment of the present invention showing two portions of tines 20 is shown in FIG. 5. The trash bar 44 of each portion of tines 20 as shown here meets the next portion with no overlap. However, as can be readily appreciated, the tines may be mounted such that the trash bar 44 of one portion may overlap the trash bar 44 of a second portion. As can be readily appreciated not every embodiment of knife guard has a trash bar or ledger bar and yet other embodiments have a retainer portion over a base portion of the tine either portion or both of which may be clad with an angular approach of the laser tool. Thus about the edges and along the bearing surfaces on either side of the tines and on either or both the cover and the bottom a laser hardened area is formed just as in the other embodiments heretofore described.

The laser used to harden the base material 14 may include using at least one of the following lasers; CO2, YAG, Diode and fiber. The laser beam consists of a column of light energy of similar wave length. These different types of lasers produce different wave lengths of light. These lasers each have their own unique characteristics, but all work well in heat treating applications.

The method of using the laser to laser harden the knife guard 10 has the advantage over other processes currently in use of involving a smaller heat effected zone that is created with the laser. The smaller heat affected zone results in less distortion of the part and minimal disruption to the microstructure of the base part, which allows better material properties in the base part after laser hardening.

The lower distortion eliminates subsequent machining and/or straightening operations, thus reducing processing time and costs. The process of heat treating the base material 14 for strength and toughness, then machining the surface (if necessary) for the section to ride on, then laser hardening can be performed easily. This process of hardening the edge after heat treat is difficult to perform without distortion or the risk of melting the edge material.

A laser tool 94 may make an angular approach to clad along the flank surfaces 34 and the ledger bar 80.

All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context. 

What is claimed is:
 1. A knife guard, comprising: a guard body comprising a base material including a mounting bar defining at least one bolt hole and at least one tine projecting forward from the mounting bar, the base material having a first hardness; and a clad material deposited on the base material, the clad material comprising a second hardness greater than the first hardness.
 2. The knife guard of claim 1, wherein knife guard includes a ledger surface that is adapted to bear against or at least face a sickle bar assembly, the ledger surface including a region of the clad material formed integrally with an outer surface of the base material.
 3. The knife guard of claim 2, wherein the base material is steel, wherein the clad material is at least 0.1 millimeter in maximum depth thickness along the base material, and less than 1 millimeter.
 4. The knife guard as in claim 2, wherein each of the tines comprises a central protrusion and a pair of flank surfaces on either side of the central protrusion extending toward a bearing surface, the flank surfaces intersecting the bearing surface at a shearing edge, the region of clad material including at least one portion formed along and extending the flanks laterally so as to extend the ledger surface and form part of the shearing edge, the clad material projecting horizontally outward from the base material to extend the flanks horizontally outward relative to the central protrusion.
 5. The knife guard of claim 4, further comprising a free region of base material that is not of the clad material, the free region being disposed above the central protrusion along the ledger surface and between first and second portions of clad material, the first and second portions being formed along the flanks so as along ledger surface and forming part of the shearing edge.
 6. The knife guard of claim 5, further comprising a trash bar extending perpendicularly to an extension direction of the at least one tine and connecting adjacent tines of the at least one tine, the free region extending along the ledger surface extending along a trash bar portion of the ledger surface defined by the trash bar, wherein the trash bar is free of the clad material.
 7. The knife guard of claim 2, wherein the mounting bar includes a ledger bar extending perpendicularly to an extension direction of the at least one tine, the ledger bar defining a ledger bar portion of the ledger surface, wherein the ledger bar portion forms part of the region of clad material along a length and an entire top surface thereof.
 8. The knife guard of claim 2, wherein more than 30% of the ledger surface is free of the region of clad material.
 9. The knife guard of claim 4, wherein the clad material on the flank surfaces extends from the ledger surface at the shearing edge toward the central protrusion a width between 0.5 millimeter and 10 millimeter and is between at least 0.1 millimeter and 3 millimeter in depth thickness on the flank surface.
 10. The knife guard of claim 1, further comprising a dilution zone wherein the clad material forms the dilution zone with the base material at a junction therebetween.
 11. The knife guard of claim 1, wherein over 85% of an outer surface of the knife guard forms an untreated region of base material, the clad material being limited to less than 15% of the outer surface.
 12. The knife guard of claim 1, wherein the base material has a hardness of less than 50 HRC, and wherein the clad material has a hardness greater than 50 HRC.
 13. The knife guard of claim 1, wherein the at least one tine comprises a plurality of tines with valleys between the tines, the at least one bolt hole comprises a plurality of bolt holes having respective bolt mounting centers aligned along a mounting axis that extends perpendicularly relative to a forward extending axis direction of the tines, the bolt holes being formed in mounting bosses formed along the mounting bar, a connecting trashbar extending perpendicularly relative to the forward extending axis direction and connecting adjacent tines, the mounting bar including a ledger bar, the ledger bar and the tines defining a ledger surface extending in a plane, wherein a sickle clearance channel is formed between the ledger bar and the trash bar, ribs at a bottom of the sickle clearance channel connecting the ledger bar and the trash bar.
 14. The knife guard of claim 13, wherein the ledger bar projects from a mounting plate portion of the mounting bar, the mounting bosses formed into the mounting plate.
 15. A cutter bar assembly including a linear array of a plurality of knife guards including the knife guard of claim 1, the cutter bar assembly comprising: a cutter bar support having a mounting flange extending in parallel relation to the linear array; a sickle bar assembly extending in a longitudinal direction in parallel relation with the cutter bar support in order to reciprocate back and forth in the longitudinal direction for cutting, the sickle bar assembly including a sickle bar and a plurality of sickle knives mounted to the sickle bar, the knife guards are arranged in side by side relation, the sickle knives are arranged in side by side relation; and wherein the knife guards and the sickle knives are in vertically overlapping relation.
 16. The cutter bar assembly of claim 15, wherein the sickle bar slides along the knife guards along a region of clad material formed on an outer surface of the base material.
 17. A method of forming a knife guard, the knife guard comprising a guard body, the guard body comprising a base material including a mounting bar defining at least one bolt hole and at least one tine projecting forward from the mounting bar, the method comprising: cladding with a laser a region of a second material on to the base material to provide a second hardness greater than the first hardness.
 18. The method of claim 17, wherein said cladding with the laser includes using at least one of the following lasers CO₂, YAG, Diode and Fiber.
 19. The method of claim 17, wherein the cladding comprises targeting and confining application of the laser to the region being of an outer surface of the guard body, the region being less than 15% of an area of the outer surface.
 20. The method of claim 19, wherein said region is deposited along a perimeter of the ledger surface at the shearing edges to form a sliding interface with a sickle bar assembly that reciprocates relative the knife guard in use.
 21. The method of claim 20, wherein at least 30% of the ledger surface comprises an untreated region free of cladding and wherein distortion is eliminated or reduced such that subsequent machining or straightening operations are not conducted on the ledger surface after said cladding.
 22. The method of claim 17, wherein the region is deposited horizontally along a opposing sides of the base material of the at least one tine, thereby forming a shearing edge with the second material.
 23. The knife guard of claim 4, wherein each one of the pair of flank surfaces comprise a base flank surface and an extended flank surface; the extended flank surfaces extending laterally outward from the flank surfaces relative to the central protrusion; and wherein the extended flank surface is comprised of the clad material.
 24. The knife guard of claim 23, wherein each of the extended flank surfaces further comprise a top extended flank surface that is coplanar with and forms part of the ledger surface.
 25. The knife guard of claim 24, wherein each of the top extended flank surfaces intersects with the extended flank surfaces at the ledger surface to form part of the shearing edge.
 26. The knife guard of claim 23, wherein the extended flank surface extends from the ledger surface of each tine toward to central protrusion a depth between 0.5 and 10 millimeters; and wherein each of the extended flank surfaces extend outwardly away from the base flank material and laterally away from the central protrusion to provide and extended flank surface depth between 0.1 and 1 millimeter.
 27. The knife guard of claim 26, wherein greater than 50% of each of the flank surface is free of clad material.
 28. The knife guard of claim 26, wherein greater than 50% of each ledger surface is free of clad material. 